This is a note to let you know that I've just added the patch titled

    KVM: x86: remove vcpu's CPL check in host-invoked XCR set

to the 3.0-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-x86-remove-vcpu-s-cpl-check-in-host-invoked-xcr-set.patch
and it can be found in the queue-3.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From 764bcbc5a6d7a2f3e75c9f0e4caa984e2926e346 Mon Sep 17 00:00:00 2001
From: "Zhanghaoyu (A)" <[email protected]>
Date: Fri, 14 Jun 2013 07:36:13 +0000
Subject: KVM: x86: remove vcpu's CPL check in host-invoked XCR set

From: "Zhanghaoyu (A)" <[email protected]>

commit 764bcbc5a6d7a2f3e75c9f0e4caa984e2926e346 upstream.

__kvm_set_xcr function does the CPL check when set xcr. __kvm_set_xcr is
called in two flows, one is invoked by guest, call stack shown as below,

  handle_xsetbv(or xsetbv_interception)
    kvm_set_xcr
      __kvm_set_xcr

the other one is invoked by host, for example during system reset:

  kvm_arch_vcpu_ioctl
    kvm_vcpu_ioctl_x86_set_xcrs
      __kvm_set_xcr

The former does need the CPL check, but the latter does not.

Signed-off-by: Zhang Haoyu <[email protected]>
[Tweaks to commit message. - Paolo]
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 arch/x86/kvm/x86.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -548,8 +548,6 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu,
        if (index != XCR_XFEATURE_ENABLED_MASK)
                return 1;
        xcr0 = xcr;
-       if (kvm_x86_ops->get_cpl(vcpu) != 0)
-               return 1;
        if (!(xcr0 & XSTATE_FP))
                return 1;
        if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE))
@@ -563,7 +561,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu,
 
 int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
-       if (__kvm_set_xcr(vcpu, index, xcr)) {
+       if (kvm_x86_ops->get_cpl(vcpu) != 0 ||
+           __kvm_set_xcr(vcpu, index, xcr)) {
                kvm_inject_gp(vcpu, 0);
                return 1;
        }


Patches currently in stable-queue which might be from [email protected] are

queue-3.0/kvm-x86-remove-vcpu-s-cpl-check-in-host-invoked-xcr-set.patch
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